Pulley device, in particular for tensioning idler or runner roller

ABSTRACT

A pulley device provides a pulley, and a bearing. The pulley has at least one C-shaped pulley part having an inner portion mounted on the bearing, an outer portion having an outer cylindrical surface dedicated to interact with a belt or a chain, and an intermediate portion extending substantially radially between axial ends of inner and outer portions on one axial side of pulley device. A grip surface portion is provided to one surface among the outer cylindrical surface of the outer ring and the inner cylindrical surface of the inner cylindrical portion of the pulley part, the grip surface portion including a plurality of indentations and recesses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application no.102019201751.7, filed Feb. 11, 2019, the contents of which are fullyincorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of pulley devices fortensioning idlers or runner rollers designed to interact with a chain ora belt, for example a distribution belt of an internal combustion engineof a vehicle.

BACKGROUND OF THE INVENTION

Such rollers are usually used to keep a constant tension on the belt orchain in a determined range or to locally modify the path taken by thechain or belt. These are called respectively tensioning idlers or runnerrollers. In runner rollers, the pulley is mounted so as to rotate on ascrew or a spindle by means of a rolling bearing, the roller then beingattached directly or indirectly to the engine block or to an element ofa tensioning idler device, for example an articulated arm or aneccentric.

Document GB 190509598 discloses a pulley comprising male and femaleoverlapping parts which are interlocking relation and form a cylindricalouter portion intended to be in contact with a belt.

A major disadvantage of this pulley is that an annular recess is formedon the outer portion adapted to support the belt when the male andfemale parts are fastened together. There is therefore a risk of anearly wear of the belt.

It is also known by document GB 141 829 a pulley comprising a peripheralpart intended to be in contact with a belt, an inner part and aintermediate part between the inner and outer parts. The pulley istightened to the outer ring of bearing, but the pulley can slightlyaxially move during the service use of pulley device. Moreover, with apulley such as disclosed, the outer part may be deformed radiallyinwards by bending under the action of the belt.

It has been proposed in document DE 202005011230 U1 to house a dampingring within a C-shaped pulley, the damping element being dedicated todamp vibrations from the belt and being suitable to limit radial inwarddeformation of outer portion of the pulley. However, the pulley canstill be deformed under heavy loads.

SUMMARY OF THE INVENTION

The aim of the invention is to overcome these drawbacks by proposing apulley which is easy to install onto a bearing, of good rigidity,adapted to avoid an early wear of the belt, and permitting an efficientsupport of the belt.

To this end, the invention relates to a pulley device suitable for abelt of chain tensioning idler or runner roller, comprising a bearingand a pulley.

The bearing comprises a rotatable outer ring and a fixed inner ring, therings being coaxial.

The pulley comprises at least one pulley part having in cross section anoverall shape of a C, and having an inner portion with an inner surfacemounted on an outer cylindrical surface of outer ring of bearing, anouter cylindrical portion having an outer cylindrical surface intendedto be in contact with the belt or the chain, and a radial intermediateportion extending substantially radially between axial ends of inner andouter cylindrical portions on one axial side of pulley device, thepulley part being formed integral and defining an open end on one axialside opposite to the intermediate portion.

According to the invention, a grip surface portion is provided to onesurface among the outer cylindrical surface of outer ring and innercylindrical surface of inner cylindrical portion of pulley part. Thegrip surface portion comprises a plurality of indentations and recesses.

According to further aspects of the invention which are advantageous butnot compulsory, such a pulley device may incorporate one or several ofthe following features:

The bearing is a rolling bearing, at least one row of rolling elementsbeing radially interposed between the inner ring and the outer ring.

The rolling elements are balls.

The rolling elements are equally circumferentially spaced and maintainedby an annular cage.

The pulley is formed by only one pulley part.

The pulley comprises two C-shaped pulley parts mounted onto the outercylindrical surface of outer ring of bearing.

Open ends of the two pulley parts axially face each other, free ends ofouter portions of pulley parts being in axial abutment.

The two pulley parts are symmetrical with respect to a transverse radialplane passing through the centre of the bearing.

The total length of the inner portions of the two C-shaped pulleysmounted onto the outer ring is at least equal to 90% of the axial lengthof the outer cylindrical surface of the outer ring.

The outer portion of pulley part is of greater axial length than that ofthe inner portion, the outer portion protruding axially on at least oneaxial side of the inner portion.

The inner portion of pulley part is cylindrical, with an innercylindrical portion.

The pulley part is made from a stamped metal sheet or blank.

The inner cylindrical portion of pulley part is force fitted onto theouter cylindrical surface of outer ring.

The grip surface portion is provided to the outer cylindrical surface ofouter ring.

The grip surface portion is provided to the inner cylindrical surface ofinner cylindrical portion of pulley part.

The grip surface portion is manufactured by a knurling process.

The pitch of indentations and recesses is comprised between 0.1 and 1mm.

The indentations and recesses of grip surface portion have a criss-crosspattern, a straight-line pattern, or any other suitable shape.

The grip surface portion is annular.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in correspondence with the annexedfigures, as illustrative examples, without restricting the object of theinvention. In the annexed figures:

FIG. 1 is an axial section of a pulley device according to a firstembodiment of the invention;

FIG. 2 is a detailed view A of the pulley device of FIG. 1;

FIG. 3 is a perspective view of a bearing provided to the pulley deviceof FIG. 1;

FIG. 4 is an axial section of a pulley device according to a secondembodiment of the invention;

FIG. 5 is a detailed view B of the pulley device of FIG. 4; and

FIG. 6 is a perspective view of a bearing provided to the pulley deviceof FIG. 4.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The pulley device 1 as illustrated in FIGS. 1 to 3 is suitable for abelt or chain tensioning idler or runner roller, and comprises a pulley2 adapted to interact with a belt or chain (not shown) and a rollingbearing 3 with a geometric axis X1.

The rolling bearing comprises a fixed inner ring 4 and a rotatable outerring 5 between which are housed two rows of rolling elements 6 and 7,which in this case are balls, two annular cages 8, 9 respectivelymaintaining the circumferential spacing of the rolling elements 6, 7,and two annular seals 10, 11.

The inner ring 4 and the outer ring 5 are concentric and symmetric withrespect to a transverse radial plane Y3 passing through the centre ofthe rolling bearing 3. The rings 4, 5 are advantageously of solid type.A solid type is to be understood as a ring obtained by machining withremoval of material, by machining, grinding, from a metal tube stock,bar stock, rough forgings and/or rolled blanks.

The inner ring 4 comprises a bore 12 dedicated to receive a fasteningscrew 13 (in dotted line) to fasten the device 1 on an external support.The inner ring further comprises an outer cylindrical surface 14 ontowhich toroidal circular raceways are formed, the raceways having incross section a concave internal profile adapted to the rolling elements6, 7.

The outer ring 5 comprises a cylindrical bore 15 onto which toroidalcircular raceways are formed, the raceways having in cross section aconcave internal profile adapted to receive the rolling elements 6, 7.The outer ring 5 further comprises an outer cylindrical surface 16.

The pulley 2 has two pulley parts 17, 18, both having in cross sectionan overall shape of a C.

The first pulley part 17 comprises an axial annular outer portion 19providing a cylindrical outer surface 20 designed to interact with aportion of the belt of the chain, and a cylindrical inner surface orbore 21.

The first pulley part 17 also comprises an axial annular inner portion22 providing a cylindrical inner surface or bore 23 into which the outercylindrical surface 16 of outer ring 5 of bearing 3 is mounted, and acylindrical outer surface 24.

The outer portion 19 is of larger diameter than that of the innerportion 22, the outer portion 19 radially surrounding the inner portion22. Advantageously, the outer portion 19 is of greater axial length thanthat of the inner portion 22, the outer portion 19 protruding axially onat least one axial side of the inner portion 22.

The first pulley part 17 further comprises an annular radialintermediate portion 25 extending substantially radially between axialends of inner and outer cylindrical portions 22, 19 on a first axialside of pulley device 1.

The first pulley part 17 then has in cross section an overall shape of aC, defining an open end 26 on one axial side of the pulley device 1. Thefirst pulley part 17 is formed integral.

The second pulley part 18 comprises an axial annular outer portion 27providing a cylindrical outer surface 28 designed to interact with aportion the belt of the chain, and a cylindrical inner surface or bore29.

The second pulley part 18 also comprises an axial annular inner portion30 providing a cylindrical inner surface or bore 31 into which the outercylindrical surface 16 of outer ring 5 of bearing 3 is mounted, and acylindrical outer surface 32.

The outer portion 27 is of larger diameter than that of the innerportion 30, the outer portion 27 radially surrounding the inner portion30. Advantageously, the outer portion 27 is of greater axial length thanthat of the inner portion 30, the outer portion 27 protruding axially onat least one axial side of the inner portion 30.

The second pulley part 18 further comprises an annular radialintermediate portion 33 extending substantially radially between axialends of inner and outer cylindrical portions 30, 27 on a second axialside of pulley device 1, the second axial side being axially opposite tothe first axial side.

The second pulley part 18 then has in cross section an overall shape ofa C, defining an open end 34 on one axial side of the pulley device 1.The second pulley part 18 is formed integral.

Advantageously, the pulley parts 17, 18 are both made of thin metalsheet or blank by folding, cutting and stamping.

Advantageously, the inner cylindrical portions 22, 30 of first andsecond pulley parts 17, 18 are force fitted onto the outer cylindricalsurface 16 of outer ring 5.

Advantageously, the two C-shaped pulley parts 17, 18 are symmetricalwith each other with respect to the radial plane Y3. The free ends ofouter portions 19, 27 of first and second pulley parts 17, 18respectively come into contact in an axial direction, the open ends 26,34 respectively being axially open to each other. The two outercylindrical surfaces 20, 28 form a surface dedicated to interact withthe belt or the chain. The pulley 2 formed by the two pulley parts 17,18 arranged in axial contact with each other is suitable for guiding,supporting the belt of the chain with an efficient manner.

According a first embodiment of the invention, the outer cylindricalsurface 16 of outer ring 5 is provided with two annular grip surfaceportions 37, 38.

As illustrated in FIGS. 2 and 3, grip surface portions 37, 38 compriseeach a plurality of indentations and recesses. Advantageously, the pitchof indentations and recesses is comprised between 0.1 and 1 mm.

Advantageously, the indentations and recesses of grip surface portions37, 38 have a criss-cross pattern, a straight-line pattern, or any othersuitable shape.

The grip surface portions 37, 38 are advantageously manufactured by aknurling process, with a knurling tool.

The outer cylindrical surface 16 comprises a first grip surface portion37 on a first axial side, and a second grip surface portion 38 on asecond axial side.

The first grip surface portion 37 extends axially on 70% of the axiallength of inner cylindrical surface 23 of inner cylindrical portion 22of first pulley part 17. Inner cylindrical surface 23 and outercylindrical surface 16, and more particularly grip surface portion 37,are in interference fit. Grip surface portion 37 increases the surfaceroughness of outer cylindrical surface 16 and permits to limit anyrelative axial displacement between first pulley part 17 and outer ring5.

Similarly and symmetrically with respect to the radial plane Y3, thesecond grip surface portion 38 extends axially on 70% of the axiallength of inner cylindrical surface 31 of inner cylindrical portion 30of second pulley part 18. Inner cylindrical surface 31 and outercylindrical surface 16, and more particularly grip surface portion 38,are in interference fit. Grip surface portion 38 increases the surfaceroughness of outer cylindrical surface 16 and permits to limit anyrelative axial displacement between second pulley part 18 and outer ring5.

The pulley 2 comprising the two pulley parts 17, 18 is then axiallyretained in both axial directions with respect to the outer ring 5 ofbearing 3. Even in case of heavy vibrations or shocks, the pulley 2 isprevented for axial movement and is suitable to efficiently support thebelt of the chain for an increased and efficient service life.

As an alternate not shown, grip surface portions 37, 38 are connectedeach other to form one unique grip surface portion on outer cylindricalsurface 16 of outer ring 5.

A second embodiment of the invention is illustrated in FIGS. 4 to 6.

The inner cylindrical surfaces 23, 31 of inner cylindrical portions 22,30 of pulley parts 17, 18 are each provided with annular grip surfaceportions 39, 40.

As illustrated in FIGS. 5 and 6, grip surface portion 39 of first pulleypart 17 comprises a plurality of indentations and recesses. Similarly,grip surface portion 40 of second pulley part 18 also comprises aplurality of indentations and recesses.

The grip surface portions 39, 40 are advantageously manufactured by aknurling process, with a knurling tool.

Inner cylindrical surface 23 of first pulley part 17, and moreparticularly the grip surface portion 39, and outer cylindrical surface16 are in interference fit. Grip surface portion 39 increases thesurface roughness of inner cylindrical surface 23 and permits to limitany relative axial displacement between first pulley part 17 and outerring 5. Similarly, inner cylindrical surface 31 of second pulley part18, and more particularly the grip surface portion 40, and outercylindrical surface 16 are in interference fit. Grip surface portion 40increases the surface roughness of inner cylindrical surface 31 andpermits to limit any relative axial displacement between second pulleypart 18 and outer ring 5.

As an alternate not illustrated, the pulley device 1 may comprise onlyone pulley part 17 or 18. According to another alternate embodiment notillustrated, the pulley device comprises a pulley 2 with two C-shapedpulley parts 17, 18 but mounted on the outer cylindrical surface 16 ofouter ring 5 with both intermediate portions 25, 33 in axial abutmentagainst each other, the open ends 26, 34 of the pulley parts 17, 18being open on opposite axial sides of pulley device 1.

Representative, non-limiting examples of the present invention weredescribed above in details with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove may be utilized separately or in conjunction with other featuresand teachings to provide improved pulley device.

Moreover, various features of the above-described representativeexamples, as well as the various independent and dependant claims below,may be combined in ways that are not specifically and explicitlyenumerated in order to provide additional useful embodiments of thepresent teachings.

1. A pulley device suitable for a belt of chain tensioning idler or runner roller, comprising: a bearing having a rotatable outer ring and a fixed inner ring, the rings being coaxial; and a pulley provided with at least one pulley part having in cross section an overall shape of a C, and having an inner cylindrical portion with an inner cylindrical surface mounted on an outer cylindrical surface of the outer ring of the bearing, an outer cylindrical portion having an outer cylindrical surface configured to contact with the belt or the chain, and a radial intermediate portion extending substantially radially between axial ends of inner and outer cylindrical portions on one axial side of pulley device, the pulley part being formed integral and defining an open end on one axial side opposite to the intermediate portion; further comprising a grip surface portion is provided to one surface among the outer cylindrical surface of the outer ring and the inner cylindrical surface of the inner cylindrical portion of pulley part, the grip surface portion comprising a plurality of indentations and recesses.
 2. The pulley device according to claim 1, wherein the pulley is formed by only one pulley part.
 3. The pulley device according to claim 1, wherein the pulley comprises two C-shaped pulley parts mounted onto the outer cylindrical surface of the outer ring of the bearing.
 4. The pulley device according to claim 3, wherein open ends of the two pulley parts axially face each other, free ends of outer portions of pulley parts being in axial abutment.
 5. The pulley device according to claim 3, wherein the two pulley parts are symmetrical with respect to a transverse radial plane passing through the centre of the bearing.
 6. The pulley device according to claim 1, wherein the inner cylindrical portion of pulley part is press fit onto the outer cylindrical surface of outer ring.
 7. The pulley device according to claim 1, wherein the grip surface portion is manufactured by a knurling process.
 8. The pulley device according to claim 1, wherein the pitch of indentations and recesses is comprised between a range of 0.1 mm and 1 mm.
 9. The pulley device according to claim 1, wherein the indentations and recesses of grip surface portion have a criss-cross pattern or a straight-line pattern.
 10. The pulley device according to claim 1, wherein the grip surface portion is annular. 